PatchSiren cyber security CVE debrief

CVE-2023-26552 Siemens CVE debrief

CVE-2023-26552 is a medium-severity out-of-bounds write vulnerability in the mstolfp function within libntp/mstolfp.c in NTP 4.2.8p15. The flaw occurs when adding a decimal point, potentially allowing an adversary to attack a client ntpq process. Notably, the ntpd daemon itself cannot be attacked via this vulnerability. The issue affects Siemens SITOP UPS1600 industrial power supply units with Ethernet/PROFINET interfaces, specifically models 6EP4134-3AB00-2AY0 (10A), 6EP4136-3AB00-2AY0 (20A), 6EP4137-3AB00-2AY0 (40A), and 6EP4136-3AC00-2AY0 (EX 20A). Published on June 11, 2024, this CVE was disclosed through coordinated government-industry advisory channels. Siemens has released firmware version 2.5.4 or later to remediate this vulnerability in affected products.

Vendor: Siemens
Product: SITOP UPS1600 10 A Ethernet/ PROFINET (6EP4134-3AB00-2AY0)
CVSS: MEDIUM 5.6
CISA KEV: Not listed in stored evidence
Original CVE published: 2024-06-11
Original CVE updated: 2024-06-11
Advisory published: 2024-06-11
Advisory updated: 2024-06-11

Who should care

Industrial operations teams deploying Siemens SITOP UPS1600 power supplies in manufacturing, energy, or critical infrastructure environments; OT security practitioners managing NTP client configurations; and asset owners requiring coordinated vulnerability response for PROFINET-connected industrial devices.

Technical summary

The mstolfp function in NTP 4.2.8p15's libntp/mstolfp.c contains an out-of-bounds write triggered during decimal point insertion. This client-side vulnerability in ntpq—NTP's query utility—permits memory corruption but does not extend to the ntpd server daemon. Attack complexity is high (CVSS:3.1/AC:H), limiting practical exploitation. Siemens has patched affected SITOP UPS1600 firmware; the fix is available through standard support channels.

Defensive priority

medium

Recommended defensive actions

Apply Siemens firmware update V2.5.4 or later to all affected SITOP UPS1600 models
Verify current firmware version through Siemens Industry Online Support portal
Review network segmentation for industrial control systems per CISA ICS recommended practices
Monitor for anomalous ntpq client activity on systems managing affected UPS units
Consult Siemens SSA-238730 security advisory for detailed remediation guidance

Evidence notes

Vulnerability description and affected product details sourced from CISA CSAF advisory ICSA-24-165-05 and Siemens product security advisory SSA-238730. CVSS 3.1 vector confirms network attack vector with high attack complexity, requiring no privileges or user interaction.

Official resources

coordinated